Process for making and spraying pesticidal invert emulsion

ABSTRACT

Disclosed is a pesticidal invert emulsion making and spraying process in which the water phase is finely dispersed in the oil phase by mechanical rotary agitation in a mixing chamber with an induced flow opposed to the flow of said phases into said chamber and under hydrostatic pressure sufficient to push invert emulsion out the outlet of said chamber through a conduit into a spray nozzle and out of said nozzle as a spray.

United States Patent Inventor Appl. No.

Filed Patented Assignee Ward Alan Smith Loukhna, Mo.

Feb. 17, 1970 July I3, 197 i Hercules Incorporated Wilmington, Del.

Continuatiolkin-part of application Ser. No. 674,416, June 20, 1967, now Patent No. 3,499,606.

rnocess r01: MAKING AND SPRAYING PESTICIDAL nwanr EMULSION 6 Claims, 3 Drawing Figs.

US. Cl

[50] FieldoiSearch 239/10, 171,304,427

[56] Reierences Cited UNITED STATES PATENTS 3,197,299 7/1965 Stulletal 239/171x 3,499,606 3/1970 Smith 239/304 Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-Michael Y. Mar Attorney-George H. Hopkins ABSTRACT: Disclosed is a pesticidal invert emulsion making and spraying process in which the water phase is finely dispersed in the oil phase by mechanical rotary agitation in a mixing chamber with an induced flow opposed to the flow of said phases into said chamber and under hydrostatic pressure sufficient to push invert emulsion out the outlet of said chamber through a conduit into a spray noule and out of said nozzle as a spray.

PATENTEnJuuslan 3.592.385

FIG. 3

WARD ALAN SMITH INVENTOR.

AGENT PROCESS FOR MAKING AND SPRAYING PESTICIDAL INVERT EMULSION The application is a continuation-in-part ofthe US. Pat. application, Ser. No. 647,416, filed June 20, l967, now US. Pat. No. 3,499,606.

This invention relates to the production of pesticidal invert emulsion sprays.

Invert emulsion (water-in-oil) sprays have an advantage over oil-in-water emulsion sprays in that they have substantially less wind drift. However, because of their non-Newtonian plastic, rheological flow properties, they are difficult to draw into the suction side of a pump. Because they are useful for the application of pesticides, processes have been developed to circumvent this difficulty.

In one process, disclosed in the U.S. Pat. No. 3,197,299, to Stull et al., the invert emulsion is made in a special spray nozzle containing a mixing chamber, at the outlet of which is a structure for forming the spray. The oil phase and the aqueous phase, at least one ofwhich comprises emulsifier material that promotes the formation of invert emulsion when the water phase is finely dispersed in the oil phase, and at least oneof which contains a pesticide, are introduced under pressure into the mixing chamber and in passing through the chamber to the outlet the water phase becomes hydraulically dispersed inthe oil phase. This process has a disadvantage, however, in that the mixing action in the mixing chamber is not as efficient as desired. Consequently, the aqueous phase to oil phase volumetric ratio generally used is lower than'desired, and the con centration of the emulsifier material generally employed is higher than desired.

In another process, the invert emulsion is made in a pump such as a centrifugal pump. The-two phases are introduced into the pump and the aqueous phase is mechanically dispersed in the oil phase, and the invert emulsion'thus formed is impelled by the pump through its outlet and connecting conduit to a spray nozzle and out of the spray nozzle as a spray. While this process is a substantial improvement comparedito the first mentioned process, the mixing action of the pump mixer is still not as effic'ient as desired.

In the process ofthis invention, mixing action of the desired efficiency is provided.

In summary, the process of this invention comprises introducing under hydrostatic pressure the aqueous phase and the oil phase at an effective volumetric ratio of aqueous phase to oil phase into a mixing chamber having an outlet in communication with spray-forming means, in said chamber mechani cally dispersing said aqueous phase in said oil phase until at least an invert emulsion is formed, by rotatably agitating said phases and inducing a flow of said phases in said chamber opposed to the introduction of said phases into said chamber, said hydrostatic pressure being sufficient to move said phases into said chamber against said flow and to push invert emulsion from said chamber through said'outlet to said spray-forming means and from said spray-forming means as spray, and passing invert emulsion through said outlet to said spray-form'- ing means and from said spray-forming means as a spray.

In one embodiment of the process of this invention the two phases are separately introduced at said hydrostatic pressure into the mixing chamber. However, in preferred embodiments ofthe process of this invention the aqueous phase and the oil phase are first commingled at an effective volumetric ratio to form a thin fiuid or Newtonian type mixture, and the mixture is introduced at said hydrostatic pressure into the chamber. Preferably the commingling is done as invert emulsion is made and sprayed. While part of all of the hydrostatic pressure can be-imparted to the two phases prior to commingling them, preferably all of the hydrostatic pressure is imparted to the mixture before introducing the mixture into the mixing chamber. In one embodiment the mixture is a premix. being made up prior to the spraying operation and gently agitated in a container during the spraying operation to maintain the rough mixture character. In this embodiment the Newtonian ratios of aqueous phase to oil phase from about l:l to about 1.

24:]. Higher and lower effective volumetric ratios, however, are within the broader concepts ofthis invention;

In the process of this invention at least one of the phases contains pesticidal material at a pesticidally effective concentration and at least one of the phases contains emulsifier material at a concentration effective to promote formation of the invert emulsion. In some embodiments both phases contain pesticidal material. Also,'in some embodiments, both' phases contain emulsifier material. The pesticidal material isusually present in solution, in dispersion or in-both solution and dispersion. The emulsifier material is usually present in solution but it can be present in dispersion alternatively or in addition to that in solution.

Oils which are used for the oil phase include petroleum distillates, fuel oil, diesel oil, kerosene, crude aromatic distil-' lates and mixed xylenes.

The aqueous phase can be pure water, but usually locally.

available water is suitable. Sometimes saltscontainingwater can be used.

Thepesticidal material comprises one or more'pesticides. Pesticides which are particularly suitable include such:herbicides as 2,4-D acid, 2,4,5'-T acid, and amine salts and alkyl or alkoxyalkyl esters of said acids, and such insecticides as DDT, malathion, toxaphene and the like.

Emulsifier material comprises one or-more-emulsifiers that promote the formation of water-in-oil emulsions. Such emuI-. sifiers are well known in the art. Preferred examplesof such include long-chain fatty amines and salts thereof, and .the alkanolamides of long-chain fatty acids.

In the usual-embodiment, oil phase-usually contains the emulsifier material as well as the pesticidal materialyIn this connection, pesticideformulations useful in the process of this invention as the oil phase have essentially the composition:

Oil 5-90 percent Emulsifier material 5-35 percent Pesticidal material 5-60 percent The residence time of the aqueous phase and oil phase in the mixing chamber isat least long enough for the invert emul.-. sion to be formed, and preferably for the invert emulsion-that has formed to reach a desired consistency. The residence time is dependent on the volume of the mixingchamber and on the flow rate of invert emulsion from the mixing chamber to the spray nozzle. These factors are readily determined.'Because of the mixing efficiency present in the process of thisinvention,

. however, the residence time can be substantially lessrthan that.

heretofore required in the pump mixer process.

The best mode now contemplated of carrying out this invention is illustrated by the accompanying drawing which formsa material part of these disclosures. In the drawing: v

FIG. 1 depicts a preferred embodiment of an apparatus for the production of an invert emulsion spray according to the process of thisinvention;

FIG. 2 is an enlarged longitudinal section of thefitting 7'in FIG. I; and

FIG. 3 is an enlarged longitudinal section of the mixing chamber 17 of the apparatus of FIG. 1.

The apparatus of FIG. l comprises an aqueous phase conduit l for conducting aqueous phase through a filter'screen 2, a check valve 3, an aqueous-phase-metering valve 4 andv a priming valve 6 to a cross junction 7 which is-connected. to an oil phase conduit 8 and to a common conduit 9. The cross junction 7, as shown in FIG. 2, is a tee-pipe fitting with the aqueous phase conduit 1 and the common conduit 9v connected to the opposite ends of the fitting, and theoil. phase conduit 8 joined to the lateral opening of-the fitting. An inner tube 5 of outside diameter substantially less than the inside diameter of the longitudinal portion of the fitting is concentrically and longitudinally disposed inside the fitting. it extends from the fitting opening joined to the aqueous phase conduit 1 past the lateral arm of the fitting but short of the fitting opening joined to the common conduit 9. The inner tube 5 functions as an extension into the fitting of the aqueous phase conduit 1. In another embodiment, the cross junction 7 is a lateral fitting without an inner tube.

The common conduit 9 which comprises a check valve 10 and a pump suction gauge 32 leads to the intake 11 ofa pump 12. The outlet 13 of the pump is connected to a feed conduit 14 which goes to the inlet 16 of the mixer 17. The outlet 18 of the mixer 17 is connected to a discharge conduit 19 which leads to a spray gun 20 having a spray nozzle 21. An engine 22 drives the pump 12 and the mixer 17. In this embodiment the pump 12 is directly driven and the mixer 17 is belt driven by a belt 23 around an engine pulley 24 and a mixer pulley 25. The engine 22 is suitably a small gasoline engine with rope starter 26. In this embodiment there preferably is a bypass conduit 31 joined to the feed conduit 14 and common conduit 9. Preferably the bypass conduit is provided with a popoff valve and a pressure gauge 15. Preferably the feed conduit 14 between the pump 12 and the mixer 17 is provided with an air bleed valve to bleed air out of the system to obtain suitable startup priming.

The mixer 17 (see Fig. 3) comprises a housing defining a chamber with an inlet 16 and an outlet 18, and a rotatable impeller 34 arranged and driven so as to induce a flow of the chamber contents toward the inlet 16. The mixer 17 is a cen trifugal pump connected in reverse so that its outlet as a pump is its inlet as a mixer, and its inlet as a pump is its outlet as a mixer. In other embodiments it can be any rotary mixer that induces flow counter to flow at the inlet thereof. An example is a fan blade rotary mixer with a housing having an inlet and an outlet oppositely disposed to each other, in which the flow is dependent on the direction of rotation of the fan blade impeller.

The intake of the aqueous phase conduit 1 is at or near the bottom of a large open container 27 of aqueous phase which in this embodiment is water. Alternatively, it can be a stream or a lake.

The intake of the oil phase conduit 8 is at or near the bot tom of a preferably portable container 28 which suitably is a small refillable tank containing oil phase. In this embodiment the oil phase comprises pesticidal material at a pesticidally effective concentration, and emulsifier material at a concentration effective for promoting the formation of a water-in oil emulsion.

The volumetric ratio of oil phase to aqueous phase in the emulsion is controlled by the water-phase-metering valve 4 and an oil-phase-metering valve 29 in the oil phase conduit 8. The residence time ofthe phases and of the invert emulsion in the mixer 17 has been predetermined by design in the embodiment shown to give an invert emulsion of desired consistency.

To prepare the apparatus of FIG. 1 for normal operation, the intake of conduit 1 is placed in the aqueous phase reser voir 27, and the oil phase reservoir 28 is filled with an oil phase comprising an emulsifiable oil conc trate of a pesti cide. The engine 22 is started. The spray gu "22 is opened or turned on, and the air bleed valve 35 is opened to bleed air from the system until the pump is primed. The air bleed valve 35 is then closed. Priming valve 6 in the aqueous phase conduit 1 is closed and then opened to reduce the water flow mo mentarily. This raises the amount of oil phase flowing into the mixer, and produces invert emulsion, which completes the priming. Then the spray gun 20 is turned off. The apparatus is now ready for normal operation.

To operate the apparatus, the spray gun 20, directed at a target over which the pesticidal invert emulsion spray is to be applied, is turned on. When the desired amount of spray has been a plied, the gun is turned off.

Whi e the spray gun 20 IS open, the oil and aqueous phases are drawn by suction of the pump 12 through the aqueous phase conduit 1 and oil phase conduit 8 into the cross junction 7 where they commingle, beginning at 33, and form the fluid mixture. The fluid mixture is drawn into pump 12 and placed under sufficient hydrostatic pressure to force the mixture into the mixer 17 against the special flow conditions that exist therein, and invert emulsion through the mixer outlet 18 through the emulsion conduit 19 to spray gun 20 and out the spray nozzle 21 as a spray.

Thus, this invention provides an improved process for making and spraying pesticidal invert emulsion.

A feature of advantage of the process of this invention is the superior mixing action that is obtained. This makes possible generally higher water-to-oil volumetric ratios, and generally lower emulsifier material concentration.

Other features, advantages, and specific embodiments of this invention will become readily apparent to those exercising ordinary skill in the art after reading the foregoing disclosures. In this connection, while specific embodiments of this invention have been described in considerable detail, variations and modifications of these embodiments can be effected without departing from the spirit and scope of the invention as disclosed and claimed.

What I claim and desire to protect by Letters Patent is:

l. A process for making and spraying a pesticidal invert emulsion, which comprises introducing under hydrostatic pressure an aqueous phase and an oil phase at an effective volumetric ratio of aqueous phase to oil phase into a mixing chamber having an outlet in communication with spray-forming means, at least one of said phases comprising pesticidal material at a pesticidally effective concentration, and at least one of said phases comprising emulsifier material at a concentration effective to promote formation of the invert emulsion in said chamber; mechanically dispersing said aqueous phase in said oil phase until at least said invert emulsion is formed, by rotatably agitating said phases and inducing a flow of said phases in said chamber opposed to the introduction of said phases into said chamber, said hydrostatic pressure being sufficient to move said phases into said chamber against said flow and to push invert emulsion from said chamber through said outlet to said spray-forming means and from said spray-forming means as spray; and passing invert emulsion through said outlet to said spray-forming means and from said spray-forming means as a spray.

2. A process according to claim 1, wherein said volumetric ratio is in a range from about 1:1 to about 24:1.

3. A process according to claim 2, wherein said phases are introduced into said chamber as a Newtonian mixture.

4. A process according to claim 3, wherein said mixture is formed by commingling said phases as invert emulsion is made and sprayed.

5. A process according to claim 4, wherein said mixture is pumped under said hydrostatic pressure to an inlet in said mixing chamber.

6. A process according to claim 5, wherein said mechanical dispersing is continued in said chamber until said invert emulsion has a desired consistency. 

1. A process for making and spraying a pesticidal invert emulsion, which comprises introducing under hydrostatic pressure an aqueous phase and an oil phase at an effective volumetric ratio of aqueous phase to oil phase into a mixing chamber having an outlet in communication with spray-forming means, at least one of said phases comprising pesticidal material at a pesticidally effective concentration, and at least one of said phases comprising emulsifier material at a concentration effective to promote formation of the invert emulsion in said chamber; mechanically dispersing said aqueous phase in said oil phase until at least said invert emulsion is formed, by rotatably agitating said phases and inducing a flow of said phases in said chamber opposed to the introduction of said phases into said chamber, said hydrostatic pressure being sufficient to move said phases into said chamber against said flow and to push invert emulsion from said chamber through said outlet to said sprayforming means and from said spray-forming means as spray; and passing invert emulsion through said outlet to said spray-forming means and from said spray-forming means as a spray.
 2. A process according to claim 1, wherein Said volumetric ratio is in a range from about 1:1 to about 24:1.
 3. A process according to claim 2, wherein said phases are introduced into said chamber as a Newtonian mixture.
 4. A process according to claim 3, wherein said mixture is formed by commingling said phases as invert emulsion is made and sprayed.
 5. A process according to claim 4, wherein said mixture is pumped under said hydrostatic pressure to an inlet in said mixing chamber.
 6. A process according to claim 5, wherein said mechanical dispersing is continued in said chamber until said invert emulsion has a desired consistency. 